Patents based on natural law must contain other inventive elements to ensure the patent in practice amounts to significantly more than a patent of the natural law itself.

Opinion (Breyer): Prometheus Laboratories, Inc. (“Prometheus”) owned two patented processes that helped doctors determine whether a given dosage level of thiopurine drugs was too low or too high. When ingested, thiopurine metabolized inside the patient’s body, and the doctor could then measure the metabolite levels using the three steps in Prometheus’ patented process. Mayo Collaborative Services (“Mayo”) announced its own, somewhat different, diagnostic test, based in part on Prometheus’ process patent, prompting Prometheus to sue Mayo for infringement. The district court granted a motion for summary judgment in favor of Mayo, finding Prometheus’ process patent invalid under 35 U.S.C. § 101, because the test merely applied laws of nature. After applying a “machine or transformation test” to determine that Respondent had “transformed” the natural law via the three-step process, the Court of Appeals for the Federal Circuit reversed. The Supreme Court found the three added steps claimed by Prometheus to transform laws of nature unconvincing. The three steps simply told the doctor to perform a routine and well-known activity by scientists. The Court held that simply altering conventional steps to the laws of nature in a highly general manner could not make those steps patentable, thus judgment for Prometheus was REVERSED.